The objective of this research is to gain a better insight into the physical and chemical nature of the thyroglobulin molecule and its role in the biosynthesis, storage and release of thyroid hormones. Among the specific goals of the project will be a study of the distribution of oligosacharide moieties and iodinated amino acids through the polypeptide sequence of thyroglobulin as reflected in tryptic peptides and the determination of amino acid sequences in the vicinity of these moieties. In addition, a continuation and extention of ultracentrifugation and rotational diffusion measurements on thyroglobulin and thyroglobulin containing complexes is proposed. Finally, a study of a model system for thyroxine biosynthesis utilizing a study of a model system for thyroxine biosynthesis utilizing micelles containing N-palmityldiiodtyrosine and related derivatives to simulate the environment of a globular protein surface is planned.